The pilot of the Gundam Deathscythe, Duo is as jolly and happy-go-lucky as Gundam pilots get. He persists in offering his friendship to the initially hostile Heero, eventually winning his antisocial comrade's trust through sheer persistence. But despite his friendly nature, Duo earns his "God of Death" nickname when he takes on Alliance and OZ soldiers in battle.
Prior to Operation Meteor, Duo was part of the spacegoing salvage organization known as the Sweeper Group, and on Earth he is assisted by the Sweepers' seafaring kinsfolk. When there is a lull in the fighting, Duo happily returns to his salvage-merchant's trade. He is distinguished by his black wardrobe, his yard-long plait and his minister's collar.
In Frozen Teardrop
After Hilde breaks up with him in MC0012, Duo travels to Mars. Getting into a terrible motorbike accident in MC0014, most of his limbs are fractured, however he is aided by Trowa Barton. Once out of the hospital, saddled with debts, he meets Hilde again, who has become a librarian in the Lanigreen Republic. After moving in with her, he begins to work to earn money to fix his motorbike, and proposes to Hilde. The two are married in MC0015, and he cuts his braid off. However, he soon leaves again, taking off into the Martian wilderness. When he returns in MC0016, Hilde has become a nun at a local church orphanage. When the priest of the church bequeaths it to them, the debts of the church are also passed on to the two, as their assets were shared in marriage- the brunt of which fall to Hilde, and so she demands a divorce from Duo, who has also incurred many debts. He accepts the divorce, but not before promising to help pay off her debts. When he returns again in MC0017 NEXT SUMMER, he discovers a child whom is also named Duo Maxwell and closely resembles him living at the orphanage, although it is not clear if the child is his biological son or not- he denies it aloud, but inwardly muses that the child would have been born in the time of his absence after marrying Hilde.
During this time, he remains a close contact and ally of the Preventers. In MC0022 NEXT WINTER, he comes to the Mars Preventer base at the request of Master Chang, the head of the base, bringing the younger Duo, whom he refers to as his son, with him. He introduces himself as only 'Father Maxwell' to Preventer agent Kathy Po and reveals that he and Master Chang were once the legendary Gundam pilots named Duo Maxwell and Chang Wufei. He seems to have been training his son to take part in the upcoming Operation Mythos, and he and Duo are present for the reawakening of Heero Yuy from cold sleep, him being the first one to greet Heero upon his awakening.
